1. Field of the Invention
The invention relates generally to apparatus for continuous strip illumination along the top edge of the perimeter of the vehicle body, and, more specifically, to a continuously illuminated clearance light strip arrangement along that perimeter.
2. Description of the Prior Art
Highway cargo vehicles of the semi-trailer or full trailer type are conventionally constructed as separate chassis units with container bodies mounted thereon and are pulled by tractor units. Vehicles codes uniformly prescribe brake, clearance and turn signal light locations and light colors. Every container body of the type includes an indentation or trough about at least a portion of the body perimeter adjacent to the roof line of the body for placement of clearance and other required lights. Conventionally, the lights placed therein are prior art units including incandescent lamps.
The light strips employed in the novel combination are emplaced horizontally within the container body trough along at least a portion of the perimeter of the container body such that lateral visibility is provided.
The light strips employed in the novel combination are constructed in accordance with optic fiber principles. Light transmission from an energizing source must travel longitudinally within the strips but also must emit, more or less uniformly, laterally. The use of fiber optic structures to convey light longitudinally and at the same time provide the needed lateral emission is known in the prior art. U.S. Pat. No. 4,763,984 discloses an arrangement including a plurality of optic fibers extending in lateral juxtaposition in a plane. The enhanced lateral light flux emission thereby provides the appearance of an illuminated strip.
In such an arrangement various techniques may be employed to enhance the required lateral emission. In the usual fiber optics arrangement light signal conveyance is optimized to provide longitudinal light transmission with a minimum of lateral emission, the latter being regarded as undesired leakage. For that purpose, the optical fiber core and cladding are constructed in accordance with well known criteria to provide light flux propagation in lower order and fundamental modes resulting in very little lateral emission. In the present combination, however, both the longitudinal transmission and lateral emission are desired. The aforementioned U.S. Pat. No. 4,763,984 describes some methods and structural variations in respect to optic fiber core size, etc. for effecting the desired lateral light emission along with sufficient longitudinal propagation. Those criteria are generally applicable to the structure of the invention although very significant structural differences vis-a-vis the prior art are included in the novel combination. These novelties will be described as this specification proceeds.
Other known prior art disclosing uses of lateral emissions from an end- energized light guide includes U.S. Pat. Nos. 2,479,500 and 2,808,502. Other prior art showing various uses of "light pipes" for various purposes includes U.S. Pat. Nos. 2,704,321; 3,723,722; 3,854,438; and 4,740,B70. None of the known prior art discloses, or makes obvious, the novel combination of the invention.